Textile apparatus



March 5, 1963 v R. P. STEIJN 3,080,135

' TEXTILE APPARATUS Filed D80. 7, 1960 2 Sheets-Sheet 1 5 FIG.3 FIG.2 5

FIG. 4

F 12 LL 2 ,lo l l f5 2 INVENTOR ROELOF P. STEIJN BY M1? March 5, 1963 R. P. STEIJN 3,080,135

TEXTILE APPARATUS Filed Dec. 7, 1960 2 Sheets-Sheet 2.

INVENTOR ROELOF P. STEIJN BY M ATTORNEY United States Patent 3,080,135 TEXTILE APPARATUS Roelof P. Steijn, Wilmington, Del., assignor to E. I. du Pont de Nemours and Company, Wilmington, Del., a corporation of Delaware Filed Dec. 7, 1960, Ser. No. 74,424 Claims. (Cl. 242-157) This invention relates to improved apparatus for handling running filaments, thread-s, yarns, strands, ribbons, films, and other thin, elongated structures. More particularly, it relates to apparatus having exceptionally high resistance to wear and characterized also by low friction when used in contact with thin, elongated structures on the run.

In the processing of a thin, elongated structure the surfaces of various apparatus elements are in contact with the structure as it is advanced. Such surfaces customarily include the surfaces of rolls, pins, guides, and the like. In commercial practice, it is highly desired that these surfaces be characterized both by long wear life and by very low friction between the running yarn or film and the various surfaces.

Many materials have been investigated in the past for the construction of textile guides, rolls, and other apparatus designed for handling moving yarns or the like. Metals such as stainless steel and aluminum have been used, frequently with a surface plating of chromium or other hard metal. Small objects such 'as guides or pins have frequently been cast from ceramic materials such as aluminum oxide or titanium oxide, while larger elements such as rolls have been fabricated from metal with a surface coating of aluminum oxide or other hard ceramic material. However, many of the modern synthetic yarns are quite abrasive and they rapidly cut through the surface of rolls or guides which have been used up to the present time. Grooves or tracks cut into the surface of textile apparatus begin to cause damage to the running yarn even when the grooves are relatively shallow. In many instances, the apparatus accordingly has an effective wear life of only a few days or weeks, after which the apparatus must be discarded or the surface renewed by grinding or by an appropriate plating or coating process, according to the nature of the surface. The short wear life of apparatus elements has been a major economic problem in many yarn applications and a need has therefore been felt for more durable apparatus.

It is an object of this invention to provide an improved surface having high resistance to wear and also characterized by low friction when used in contact with thin, elongated structures on the run. A further object is to provide improved apparatus for handling moving thin, elongated structures, said apparatus being characterized by high resistance to wear as well as low friction.

It has now been found that textile apparatus in which the surfaces contacting the moving elongated structures are comprised substantially of a continuous surface of chromic oxide (chromium sesquioxide, Cr O have exceptionally high resistance to wear. The surfaces are also characterized by low friction when suitably finished in accordance with known methods. The apparatus may be fabricated from metal and the yarn-contacting surface may subsequently be coated or sprayed with chromic oxide; or the entire article may be molded or otherwise fabricated irom chromic oxide. If desired, the chromic oxide surface my contain up to about 50% of another metallic oxide ceramic material, such as aluminum oxide, tin oxide, or titanium dioxide. In fact, a composition containing about 50-90% chromic oxide and 50-10% aluminum oxide is preferred as a coating material owing to the ease with which the surface may be formed.

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The invention will be more fully understood by reference to the accompanying drawings, in which:

FIGURE 1 is a transverse vertical sectional view of a roll having the novel surface of the invention;

FIGURE 2 is a similar view of a flanged separator roll having :the novel surface of the invention;

FIGURE 3 is a similar view of the upper half of a traverse roll having the novel surface of the invention;

FIGURE 4 is a similar view of a draw pin having the novel surface of the invention;

FIGURE 5 is a top view of a yarn guide in which the yarn-contacting surfaces are the novel surfaces of the invention;

FIGURE 6 is a top view of a pin convergence guide in which the convergence pins have the novel surface of the invention;

FIGURE 7 is a transverse vertical sectional view of a pigtail guide in which the yarn-contacting surfaces are the novel surfaces of the invention; and

FIGURE 8 is a diagrammatic view of yarn passing from a spinneret over various guides and then to a wind-up roll.

Turning now to the figures, FIGURE 1 illustrates a right circular cylindrical metallic roll 1 suitable for use as a feed roll or for general purpose applications in textile operations. The roll has hollowed portions 2 at either end and central bore 3 by which the roll may be supported and rotated by a shaft. To the periphery 4 of the metallic portion of the roll is bonded a continuous coating 5 of chromic oxide. The thickness of the chromic oxide coating is greatly exaggerated in FIGURES 15 and FIGURE 7.

FIGURE 2 illustrates a right circular cylindrical metallic roll 6 having central bore 3 and flanges 7. Such a roll is suitable for use as a. separator roll in textile operations. To the periphery 4 of the metallic portion of the roll is bonded a continuous coating 5 of chromic oxide. The chromic oxide coating follows the contour of the flanges at the ends of the roll.

FIGURE 3 represents the upper half of a traverse roll 8 having hollowed portions 2 at either end and central bore 3 by which the roll may be supported and rotated by a shaft. The surface of the roll contains helical groove 9 for traversing yarn. As in the rolls of FIGURE 1 and 2, a continuous coating 5 of chromic oxide is bonded to the periphery 4 of the metallic portion of the roll. The chromic oxide coating is bondedto the sides and bottom of the groove 9 as well as to the surface of the roll.

FIGURE 4 shows a substantially cylindrical metallic draw pin .10. A continuous coating 5 of chromic oxide is bonded to the periphery 4 of the metallic portion of the pin. One end 11 of the pin is left bare, the pin thereby being adapted for insertion into a socket in a block (not shown) heated by suitable means so that the draw pin may be heated to the desired temperature. The metallic portion of the pin is suitably made of copper to promote uniformly rapid flow of heat.

In operation, yarn 12 is passed from a feed roll, wrapped one or more times about the draw pin, and is then passed to a draw roll operating at a higher peripheral speed than the feed roll.

FIGURE 5 illustrates a top sectional view of a metallic yarn guide 13 having four fingers 14 between which ride yarns 15, seen in cross section. To the periphery 4 of the metallic portion of the guide is bonded a continuous coating 5 of chromic oxide. The chromic oxide coating follows the contour of the fingers throughout the portion of the guide normally contacted by the yarn.

FIGURE 6 illustrates a cross pin convergence guide suitable for use in many textile applications. Cylindrical pins 16, fabricated of solid chromic oxide, are mounted in holes 17 drilled diagonally through cylindrical stainless steel holder 18, which is suitably threaded at one end 19 for mounting the assembly in the desired position on a textile processing apparatus. Set screws 2d are provided to fix the cylindrical pins 16 in suitable position longitudinally in holes 17 to maintain the pins in the desired crossed configuration.

FIGURE 7 is a transverse section of a length of heavy Wire 21 bent into :a loop 22 at one end to form a pigtail guide. A continuous coating of chromic oxide is bonded to the periphery 4 of the wire in the vicinity of the loop.

In FIGURE 8 the yarn is spun from a spinneret 23 shown diagrammatically and collected into a yarn 12 by means of pin convergence guide 16, passed over feed roll 1 with separator roll 6, draw pin 10, draw roll 24 with separator roll '6, and finally to wind-up roll 25. Contacting elements 16, 1, 6, i0, 24, and 6 each have a hard, low friction continuous surface 5 containing at least 50% chromic oxide, the spinneret 23 and wind-up roll 25 acting as means for delivering the yarn to and from the contacting elements.

In preparing the novel apparatus of the invention, conventional fabricating techniques may be employed. Solid chromic oxide guides, pins, or other articles are prepared by molding or pressing chromic oxide powder in the desired shape, fusing or sintering the shaped article, and then grinding or lapping the yarn-contacting surface to the desired smoothness.

In an alternative method especially useful for larger anticles, metallic apparatus of the desired design is first fabricated in the usual manner. Stainless steel, aluminum, or any other metal generally suitable for the fabrication of metallic apparatus may be used. The surface or surfaces to be provided with the chromic oxide coating are then cleaned to free them from particles of rust, organic substances, and other materials. Preferably the surface is roughened, such as by sand blasting it.

The chromic oxide coating is then applied to the metallic apparatus by any of the various known flame-spraying, arc spraying, or coating methods using chromic oxide in the form of a rod or in powdered form, the chromium oxide being heated to the molten state and projected or sprayed upon the metallic surface in the form of fine globules which are thereby bonded to the metallic surface. The heating of the chromic oxide may be accomplished by means of a flame produced by chemical burning, such as an oxyacetylene flame, either in the form of a continuous fiarne or as a continual series of detonations. Heating may also be accomplished by electrical means, such as a plasma jet or arc. Examples of flame-spraying and coating procedures of this general type are described by Poornran et al. in US Patent 2,714,563; by Stackhouse et al. in Product Engineering, vol. 29, pages 104-6, December 8, 1958; by Ault in the Journal of the American Ceramic Society, vol. 4-0, pages 69-74, March 1, 1957; and by Oechsle in Metal Finishing, volume 55, pages 67-71 and page 76, December 1957.

The as-sprayed chromic oxide surface is not suitable I as such for use on apparatus for handling textile materials and films, since the as-sprayed surface is too rough and contains numerous sharp surface irregularities which not only result in a high coefficient of friction but also cause damage to the yarns and films which are processed thereon. The as-sprayed surfaces are therefore smoothed down 7 l by grinding, lapping, or brushing procedures in preparing the surfaces for actual use in their various applications. If desired, the surfaces may be ground down substantially smooth; however, for minimum friction and for maximum resistance to wear, the rough surface of the assprayed chromic oxide coating is converted to a surface characterized by smoothly rounded nodules. This is accomplished by smoothing down the surface only partially by means of brush-finishing or tumbling techniques. For instance, an abrasive material such as particles of silicon carbide may be applied in an aqueous slurry to the assprayed surface by a power-driven brush sufficiently long to smooth olf sharp peaks in the surface and to reduce the surface roughness to a value in the range 70-250 R.M.S. (root mean square) microinches. By terminating the procedure at this point, the chromic oxide coated surface is found to contain numerous smoothly rounded nodules. In use, apparatus provided with such a surface is characterized by low coefficient of friction, in the range 0.18 to 0.22 for most textile yarns, and an exceptionally long wear life. If a smoother surface is desired, the brushing technique may be continued until a lower level of surface roughness is achieved. For most purposes, a surface roughness in the range of about 15-40 R.M.S. microinches is regarded as being quite smooth.

The as-sprayed chromic oxide coating may also be converted to a smoothly rounded nodular surface by means of a tumbling technique. For instance, the apparatus having the as-sprayed chromic oxide coating may be placed in 'a tumbling tank having a rubber internal lining and tumbled in an aqueous slurry of 240 grit size silicon carbide for a time sulficient to reach but not go below 70-250 R.M.S. microinches surface roughness and to smooth off sharp peaks in the surface. The time required to achieve this result depends upon conditions, but fr'eqently is in the range of from 2 to about 4 hours. Of course, if a smoother surface is desired, the tumbling process is carried out for a longer time.

Although the apparatus may be fabricated from or coated with pure chromic oxide, compositions comprising mixtures of metallic oxides containing at least about 50% chromic oxide are useful. Mixtures of 50-90% chromic oxide and 50-10% aluminum oxide are preferred compositions in the fabrication of textile apparatus flamesprayed or coated with the chromic oxide coating, since the mixtures can be processed in the flame-spraying or coating technique even more readily than pure chromic oxide and are also more readily brushed to the desired surface characteristics.

The expression thin elongated structure is used herein to denote a shaped article, particularly a shaped article of a polymer, in which at least one dimension of the structure is relatively quite large and at least one dimension of the structure is quite small. characteristically, the cross section of the structure is also substantially uniform at any point on the long dimension of the structure. The expression therefore comprehends ribbons and films as well as filaments and yarns.

The nature of the invention will be further illustrated by the following examples, although they are not intended to be limitative.

Example I Cylindrical draw pins, composed of mild steel and having the dimensions 1.5 inches (length) x inch (diameter), are provided with various surfaces, as follows. One set of pins is chrome plated and then polished smooth, the final step being a diamond lapping. The thickness of the polished chrome plating is 3 mils. Additional sets of the steel pins are provided with various ceramic coatings by flame-spraying the sand-blasted surface of the pins with the appropriate ceramic material, using a detonation gun. The ceramic coated pins are then ground down to a high polish, the final step being a diamond lapping. In each case the thickness of the coating is approximately 3 mils. In a series of experiments, the wear resistance of the various pins when exposed to moving yarn is then recorded. In each case, the yarn is 40 denier, 27 filament, zero twist, dull yarn composed of polyethylene terephthalate containing 2% TiO The yarn speed is 600' yards per minute, the contact angle of the yarn around the pin is and the tension of the yarn approaching the pin is controlled at 10 grams. The pins are examined at frequent intervals, and the test is stopped as soon as a distinct wear track is observed on the surface of the pin. The time required for the appearance of a distinct wear track in the pins tested is given below for each of the coating materials employed.

Pin surface composition: Wear time, hours Metallic chromium 1 A1 -6 T 10 (E 0 90% Cl'203/10% A1203 80% c p /20% A1 0 100 CI203/50% A1203 75% Cr O /25% TiO 100 Example 11 Solid ceramic pins, 1.5 inches long and inch in diameter, are molded by conventional techniques and are then polished smooth in a series of grinding steps, the final step being a diamond lapping step. The pins are then subjected to the same yarn wear test described in Example I. The results are reported below.

Pin surface composition: Wear time, hours T10 10 A1 0 3o CZ'gOg 75% Cr O /25% A1 0 100 Example 111 A steel draw roll of the type shown in FIGURE 1, 4 inches long and 6 inches in diameter, is roughened by sand blasting and a continuous coating of chromic oxide 6 mils thick and having a surface roughness of about 250 r.m.s. (root mean square) microinches is flame-sprayed upon the surface of the roll using a detonation gun. The coated surface is brush finished to a surface roughness of about 200 r.m.s. microinches using a power driven brush and an aqueous slurry of 240 grit size silicon carbide. The finished surface is a smoothly rounded nodular surface having a coefficient of friction of 0.2.

When employed in the drawing of 40-denier, 27-filament, zero twist, dull yarn composed of polyethylene terephthalate containing 2% TiO draw rolls prepared as described above have a useful wear life in excess of 100 times the wear life of a similar steel draw roll provided with a smoothly rounded nodular surface of metallic chromium (matte-finished chrome plate).

A sand-blasted aluminum roll, when flame-sprayed with chromic oxide and finished as described above, has a long wear life similar to that of the steel roll provided with the chromic oxide surface.

Example IV A steel pigtail guide of the type shown in FIGURE 7, having an overall length of 5 inches and an inside loop diameter of inch, is sand-blasted at the looped end to a point on the guide well past the loop. A mixture of 50% chromic oxide and 50% titanium dioxide is flamesprayed onto the guide to provide a continuous coating about 0.0015 inch in thickness and the coated guide is lightly brush finished. When employed with dull polyethylene terephthalate yarn, the guide has an excellent wear life.

Similar results are obtained by flame-spraying a mixture of 50% chromic oxide and 50% tin oxide onto a guide of the above type and lightly brush finishing the coated guide.

It will be apparent that many widely different embodiments of this invention may be made without departing from the spirit and scope thereof, and therefore it is not intended to be limited except as indicated in the appended claims.

I claim:

1. In an apparatus for handling a moving thin elongated structure, a contacting element having a hard low-friction continuous surface containing at least about 50% chromic oxide; and means for delivering the said elongated structure to and from the said contacting element.

2. The apparatus of claim 1 in the form of .a metallic pin having a hard ceramic coating firmly bonded thereto containing chromic oxide.

3. The apparatus of claim 1 in which the said surface contains from 50% to 90% chromic oxide; the balance being a ceramic metallic oxide selected from the group consisting of titanium dioxide, tin oxide and aluminum oxide.

4. The apparatus of claim 1 in the form of a draw pin.

5. The apparatus of claim 4 in which the draw pin has an interior copper core and firmly bonded thereto a coating containing at least 50% chromic oxide.

6. The apparatus of claim 1 in which the coefficient of friction between the said surface and a textile yarn is in the range of 0.18 to 0.22.

7. The apparatus of claim 1 which comprises a smoothly rounded nodular surface in which the surface roughness is in the range of to 250 root mean square microinches.

8. The apparatus of claim 1 in the form of a solid ceramic pin comprising at least 50% chromic oxide.

9. The apparatus of claim 1 which comprises a substantially smooth surface having a surface roughness of less than 70 root mean square microinches.

10. The apparatus of claim 9 in which the surface roughness is in the range of 15 to 40 root mean square microinches.

References Cited in the file of this patent UNITED STATES PATENTS 2,369,266 Thurnauer Feb. 13, 1945 2,498,622 Machel Feb. 21, 1950 2,843,507 Long July 15, 1958 2,975,078 Royfield Mar. 14, 1961 FOREIGN PATENTS 839,326 Great Britain June 29, 1960 OTHER REFERENCES Dupont: Textile Fibers, Bulletin x-9l, October 1958.

Disclaimer 3,080,135.--R0el0f P. Stez'jn, Wilmington, Del. TEXTILE APPARATUS. Patent dated Mar. 5, 1963. Disclaimer filed May 16, 197 3, by the assignee, E. 1. 01a Pom? de N emoaas and Company. Hereby enters this disclaimer to claims 1-10 of said patent.

[Ofiicial Gazette J anuary 8,1974] 

1. IN AN APPARATUS FOR HANDLING A MOVING THIN ELONGATED STRUCTURE, A CONTACTING ELEMENT HAVING A HARD LOW-FRICTION CONTINUOUS SURFACE CONTAINING AT LEAST ABOUT 50% CHROMIC OXIDE; AND MEANS FOR DELIVERING THE SAID ELONGATED STRUCTURE TO AND FROM THE SAID CONTACTING ELEMENT. 